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A simple route to synthesize ultra-high molecular weight particle brushes by surface-initiated atom transfer radical polymerization (SI-ATRP) from silica nanoparticles was developed. SiO2-g-PMMA and SiO2-g-PS particle brushes were prepared with different [SiO2–Br]0 concentration of initiating sites on the surface of the nanoparticles. Ultra-high MW (> 106) SiO2-g-PMMA particle brushes with narrow molecular weight distribution (< 1.3) and different grafting densities were synthesized. The grafting density of SiO2-g-PMMA particle brushes decreased with increasing target degree of polymerization. The same conditions were applied to the synthesis of SiO2-g-PS particle brushes. However, due to the lower propagation rate constant of styrene, coupling between SiO2-g-PS particle brushes occurred and also some fraction of unattached homopolystyrene was generated by the thermal self-initiation of styrene, preventing successful synthesis of ultra-high MW SiO2-g-PS particle brushes. [ABSTRACT FROM AUTHOR]

Gradient copolymer grafts of styrene and α-tert-butoxy-ω-vinylbenzyl-poly(glycidol ethoxyethyl ether) (PGLet), a precursor of a-tert-butoxy-ω-vinylbenzyl-polyglycidol macromonomer (PGL), were prepared on silicon wafers via a surface-initiated activator generated by electron transfer radical polymerization (AGET ATRP). Silicon plates with previously attached 2-bromoisobutyrate served as a macroinitiator for the AGET ATRP (activator generated by electron transfer) of styrene and PGLet. The copolymers' gradient P(S-co-PPGL) of composition and thickness was obtained by a simple method where the plates were slowly removed from reaction mixture using a step motor. PGLet was added continuously (dropwise) into the reactor during withdrawal of the plates from solution in order to increase the relative concentration of PGLet in polymerization mixture. A range of strategies of making grafts was tested. The plates with copolymers grafts were analyzed by various techniques, like XPS, ellipsometry, and FTIR spectroscopy. The results indicate that the AGET ATRP process is dependent on the styrene/PGLet macromonomer ratio in the polymerization mixture. Under optimal conditions, the addition of PGLet during polymerization and subsequent deprotection of hydroxyl groups of PGLet permit to obtain plates with a novel copolymer layer with composition, thickness, and wettability gradient. Plates with chemical composition of copolymer grafts gradient served as versatile supports with controlled hydrophilic/hydrophobic area and were suitable for tailored deposition of particles. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Block copolymers can self-assembly into tailored nano-spheres. • Obtained nano-spheres can be an efficient templates for nanoparticles synthesis. • Amine groups of the nano-spheres are required for multifunctional nanoreactor. Abstract This paper demonstrates the universal character of nano-spheres, formed from block copolymers of poly(2-(dimethylamino)ethyl methacrylate)- block -polystyrene (PDMAEMA- b -PSt) via polymerization induced self-assembly (PISA), as multifunctional templates for tailored nanoparticles (NPs) synthesis. Due to the presence of basic amine groups located within the shell of spherical PDMAEMA- b -PSt copolymers nano-objects, three types of inorganic precursors were loaded into the shells through electrostatic interactions. Both redox-type and sol-gel chemistry were used to successfully immobilize the in situ formed gold, or silica and titania NPs, respectively. The hybrids could be potentially used as catalysts or dielectric materials. [ABSTRACT FROM AUTHOR]

Spherical poly(acrylic acid)- block -polystyrene (PAA- b -PS) nano-objects were prepared via polymerization induced self-assembly (PISA) and used as templates for the synthesis of silver nanoparticles (Ag NPs). The PAA shells on the spheres acted as templates for the formation of immobilized Ag NPs by loading Ag + ions followed by reduction. The templates covered with discrete Ag NPs showed surface-enhanced Raman spectroscopy (SERS) effect as substrates for adenine detection and high catalytic activity for reduction of 4-nitrophenol to 4-aminophenol. [ABSTRACT FROM AUTHOR]

Core–shell molecular bottlebrushes with various topologies and with poly ( tert -butyl acrylate)- b -polystyrene (P t BA- b -PS) block copolymer side chains were synthesized via atom transfer radical polymerization (ATRP). After hydrolysis of the P t BA segments and their conversion to poly (acrylic acid) (PAA), the materials were used as templates to prepare titania nanoparticles. Transmission electron microscopy (TEM) images showed that the particles retained the characteristic shape of the templates, including branches and cylindrical geometry. The cylindrical dimensions, i.e. diameter and length, were controlled by the number average degrees of polymerization of the PAA side-chain block and the polymethacrylate backbone, respectively. Thermogravimetric analysis (TGA) showed the weight fraction of inorganic content ranged from 17% to 35%, depending on the ratio of the length of PAA and PS blocks. [ABSTRACT FROM AUTHOR]

Abstract: A series of well defined ABA, 3-arm star and bottle brush type copolymers, containing soft poly(n-butyl acrylate) (PBA) blocks and hard blocks of polystyrene (PS) were synthesized by atom transfer radical polymerization (ATRP). Small angle X-ray scattering was used to study the phase separation in these systems and dynamic mechanical analysis and tensile tests were performed to characterize their thermo-mechanical properties. The specific molecular architecture has a major effect on the copolymers self-organization and material properties. The linear ABA type copolymers showed micro phase separation and thermoplastic elastomer (TPE) behavior only at very high PS content. The change of molecular architecture from linear to 3-arm star type resulted in an improved phase separation at lower PS content and better thermoplastic elastomer properties. In contrast the specific brush type molecular architecture seems to prevent the micro phase separation of the PBA and PS components, resulting in amorphous bulk material with single glass transition temperature. [Copyright &y& Elsevier]

Abstract: High molecular weight polystyrene (PS) was synthesized by ATRP. Under atmospheric pressure (1bar), PS with Mn up to 200,000 was prepared using either ARGET or ICAR ATRP. Under high pressure (6kbar), higher molecular weight PS could be obtained due to accelerated radical propagation and diminished radical termination in polymerization of styrene. Therefore, it was possible to synthesize PS with Mn >1,000,000 and Mw /Mn <1.25 using AGET ATRP under a pressure of 6kbar at room temperature. This is the highest molecular weight linear PS prepared by a controlled radical polymerization. [Copyright &y& Elsevier]

Spherical nano-objects composed of poly(acrylic acid- stat -acrylamide)- block -polystyrene (P(AA- stat -Am)- b -PS) were prepared via polymerization induced self-assembly (PISA) and used as templates for the synthesis of hybrid Ag@P(AA- stat -Am)- b -PS. These well-defined hybrids were used as effective surface-enhanced Raman spectroscopy (SERS) supports for adenine detection as targeting molecule. Due to the presence of acrylamide units, the interactions between carboxyl groups, –COOH and AgNP were tuned, leading to the improvement of SERS effect in comparison to the system based on PAA– b -PS. SERS activity for Ag@P(AA 56 - stat -Am 19)- b -PS 375 (ratio 1:1) was ~20 times higher (36x104) as compared to the reference system; PAA 86 - b- PSt 380. [Display omitted] • (PAA- stat -PAm)- b -PS nanoobjects were prepared by PISA. • They were used as templates for Ag nanoparticles synthesis. • Ag@P(AA- stat -Am)- b -PS hybrids were used as effective SERS supports. [ABSTRACT FROM AUTHOR]

A new concept of utilization of particle-polymer hybrids as multifunctional additives for polymer blends was introduced in this study. Graphene oxide particles with short densely grafted polystyrene brushes (GO- g -PS) were prepared by surface-initiated atom transfer radical polymerization (SI-ATRP). Melt rheology studies revealed that GO- g -PS suppressed the phase separation of miscible poly(methyl methacrylate)/poly(styrene- co -acrylonitrile) (PMMA/SAN) blends. The studies suggested specific interactions of GO- g -PS with the PMMA phase and this was confirmed based on calculations of activation energies of segmental relaxations by broadband dielectric spectroscopy (BDS). These unusual interactions of GO- g -PS with PMMA phase were assigned to the specific and precise architecture of the GO- g -PS particles as well as chemical nature of PS polymer brushes. The short chains of PMMA and PS provide miscibility originating from UCST behavior of PMMA/PS blend of short polymer chains. Additionally, BDS also revealed improved charge transport in PMMA/SAN blend in presence of GO- g -PS hybrid. Image 1 • New multifunctional additives for miscible polymer blends were introduced. • The graphene oxide plates grafted with short dense polystyrene brushes were used. • The increase of LCST of the PMMA/SAN blends enriched with GO-g-PS was observed at very low filler loading. • The improved interactions of synthesized hybrid particles with PMMA component of miscible blend were proved. [ABSTRACT FROM AUTHOR]